Autophagy in monocyte-derived cells. Monocytes are plastic cells that differentiate into M1-polarized macrophages on exposure to GM-CSF and M2-polarized macrophages on M-CSF exposure. Zhang et al report that autophagy is required for monocyte differentiation into macrophages and prevents cell death. Autophagy is also activated in monocytes exposed to GM-CSF and IL-4 to generate dendritic cells,¹  and to MCP1 to generate pre-osteoclasts.⁹  In addition, autophagy is activated in lipid-loaded macrophages (foam cells) found in atherosclerotic lesions¹⁰  and in some infected macrophages to favor pathogen elimination and antigen presentation (not shown). Professional illustration by Alice Y. Chen.